Scuba-diving mouthpieces of various kinds have been known and used for many years. The great majority of such mouthpieces are not customizable for individual divers, but some customizable scuba-diving mouthpieces have been known or used. Examples of customized or customizable scuba-diving mouthpieces are those shown in U.S. Pat. No. 3,107,667 (Moore), U.S. Pat. No. 3,844,281 (Shamlian), U.S. Pat. No. 3,929,548 (Shamlian), and U.S. Pat. No. 4,136,689 (Shamlian), and U.S. Pat. No. 5,305,741 (Moles) U.S. Pat. No. 5,031,611 (Moles). These U.S. patents are herein incorporated by reference.
Despite advances in recent years, there are many problems and shortcomings with scuba-diving mouthpieces as known in the prior art. Perhaps the most common problem relates to mouth fatigue experienced by scuba divers. Mouthpieces are typically held in place by means of the diver's bite on retaining members which project inwardly from a lip-engaging portion to positions between the upper and lower teeth. This not only places significant pressures on small portions of the diver's teeth, i.e. the portions engaging the retaining members, but also the constant muscle pressure needed for secure retention of such mouthpieces can cause significant muscle strain and aching of the jaw and other portions of the head connected to the jaw bone. The fatigue is exacerbated when a recreational scuba diver dives for an extended period of time without the benefits of an ergonomic or customizable mouthpiece.
Customizing the surfaces of such retaining members to match the tooth surfaces, as in the above-mentioned patents to Shamlian—U.S. Pat. No. 3,844,281 and U.S. Pat. No. 3,929,548 ameliorates the problem, however, the improvement is very limited because of the fact that contact with the inwardly-projecting retaining members is limited to only a few teeth.
Greater tooth contact is possible with scuba-diving mouthpieces such as the customized mouthpiece disclosed in the above-mentioned patent to Moore (U.S. Pat. No. 3,107,667). The tooth-engaging portions in such a device extend well back along the line of the molars on either side of the mouth. Such extension provides a greater lever arm, thereby reducing the pressure necessary to hold the mouthpiece in the mouth. Because of this, mouth fatigue should be reduced. However, the process used to manufacture such a mouthpiece is extremely complex, requiring steps such as making wax replicas of the maxillary and mandibular impressions of the mouth, mounting such replicas in the appropriate relative positions of the partly-opened mouth, carving, uniting tube and tooth impression portions, plaster forming, introducing vulcanizable rubber, separating plaster from formed rubber, and other steps.
The complexity of this manufacturing process rules out quick preparation, such as would be required in a diving equipment shop. Furthermore, the process can produce mouthpieces that are less than satisfactory in comfort. In some cases, this is because the relative positions of the relative maxillary and mandibular portions may not be natural. In other cases, this may be because the relative positions are not sufficiently closed. The problem of unnatural jaw position placement is accentuated for the 20% or so of the population whose jaws are developed well away from normal patterns. In each case, improper relative placement, even in customized scuba-diving mouthpieces, exacerbates the usual problems of jaw fatigue.
The problems of jaw fatigue and joint strain during long use are accompanied by a related problem—a tendency toward an inability by the diver to easily maintain the mouthpiece in the proper orientation, particularly when pressures are applied to the mouthpiece from outside the diver's mouth. Constant musculo-skeletal force applied to a device or load promotes fatigue and eventual failure to hold the device. Unwanted pressures on the mouthpiece grip may come about from water currents (relative to the diver), contacts made with other divers or diving apparatus, as well as a variety of other causes. It is essential, of course that the diver's mouthpiece, which is the sole source of air, remains in place and remains safe and usable. Thus, the concern about pressure interfering with the grip of the diver on his or her mouthpiece is a safety issue that requires further attention and is a continued source of research and development efforts.
Some of the problems with current scuba-diver mouthpieces can be understood better by reviewing the sections of the mouth, jaw, and teeth of a typical person that are in use when a mouthpiece is employed during diving activities. The jawbone is a lengthy angled member that pivots with respect to the skull about the temporo-mandibular joint well back from the mouth with respect to the jawbone. This joint is typically positioned considerably above the level of the teeth and well behind the position of the teeth. From this joint, the jaw has a generally downwardly and slightly forwardly extending portion which extends generally to a position rearwardly spaced from the teeth, and a more forwardly, but still downwardly, extending portion which carries the teeth of the lower jaw and extends forwardly beneath the upper jaw. The angle between the two portions of the lower jaw is referred to herein as the “jaw angle.”
Opening and closing muscle tissue masses are secured to the jaw at positions forward of the jaw joint, but well rearward of the teeth. The muscles secured to the lower jaw create a lever arm which extends from the jaw joint all the way to the point of contact pressure of the lower jaw with either the upper jaw or with whatever is being bitten and exists between the lower and upper jaw area. Mouthpieces, including that of the present invention, are essentially bitten to ensure proper insertion—at least upon original insertion into the mouth.
When using a typical diving mouthpiece, or a customized diving mouthpiece such as those shown in the aforementioned Shamlian patents (U.S. Pat. No. 3,844,281 and U.S. Pat. No. 3,929,548), the lever arm of the lower jaw extends from the jaw joint all the way forward to the position of the eye teeth where the mouthpiece is gripped by biting between the diver's teeth.
Two separate problems are created when the mouthpiece contact occurs in this manner at the forward position in the mouth:
First, since the distance from the center of muscle effort is long, a significant increase in muscle force is necessary to stabilize and retain the mouthpiece. This is what causes the muscles to quickly fatigue and often causes pain. The initial pain is often followed by jaw aches and headaches. A second and related problem of this long lever arm is created when standard mouthpieces, or customized mouthpieces of the Shamlian type, in that there is a severe increase in pressure within the jaw joint, which resides well back in the head or skull portion of the user.
If the contact location is extended to the back of the mouth, the lever arm is shortened and advantages are achieved, including a reduction in the muscle force necessary to hold the mouthpiece and a reduction in the corresponding jaw pressure. Lengthening the mouthpiece retention piece to allow contact at a more rearward position in the mouth creates a shorter, and thus more favorable, lever arm. This resists torque from movement of the diver's regulator. That is, a better grip can be maintained with less exertion during the gripping when “biting” the mouthpiece.
Another unresolved problem that remains is that the extension of the posterior bite pieces have been difficult to use or unworkable due to the variability in the jaw alignment of different individuals. Only a completely customized bite portion would compensate for this problem. The variability in the angle between the teeth of the upper and lower jaws continues to exist as a major problem for mouthpieces. Such variability is caused by differences in the aforementioned lower jaw angle and also by the angle of the upper jaw with respect to the lower jaw.
Another major problem with previous customizable mouthpieces is based upon the fact that extreme variability exists with front teeth (incisors) in that they generally have a unique vertical direction relative to the back teeth for each individual and when these teeth extend downwardly more than an average distance, they tend to partially cover the air intake of the mouthpiece. When the diver bites on the bite portions of the mouthpiece, this creates a partial reduction and increased turbulence of the air flow. The diver tends to experience “starving” for air in this circumstance—an unacceptable safety hazard.
Mouthpieces of the prior art include a lower front flange of the mouthpiece at a position vertical and directly below the upper flange. However, when the typical jaw opens it follows a variable path that is both downward and backward with respect to a reference point. At a jaw opening position of 4-6 mm (open), which is the average mouth opening for insertion of a diving mouthpiece, the lower jaw typically must come forward to grip the bite portions and seal against the lower front flange. This tends to cause significant muscle strain, and places the jaw joint in an unnatural position complete with a heavy load on the joint.
Known customizable scuba-diving mouthpieces have been unable to easily and properly accommodate a wide variety of mouth and teeth configurations. It would be desirable to have a customizable scuba-diving mouthpiece that can provide excellent and easy diver engagement for a wide variety of divers. In addition, it would be extremely useful to provide a mouthpiece which could be used multiple times by different divers that would accommodate each individual diver's unique jaw and teeth configuration. Such an arrangement would be of particular importance in the dive rental business.
There remain still additional problems related to creation of a completely customizable scuba-diving mouthpiece. Broad-reaching customizability causes problems in maintaining strength and integrity in the mouthpiece at points of pressure and torque. For example, materials, which are both readily formable and of acceptable flexibility may be weakened by torque applied at certain points. More specifically, a torque applied on the mouthpiece can cause tearing of such material unless mouthpiece construction and design allow for minimization or elimination of the risk of damage. Furthermore, customizing critical surfaces of such a mouthpiece must be carried out without degrading the structural integrity and strength of the mouthpiece.
Still another concern with customized scuba-diving mouthpieces of the prior art is that such mouthpieces do not very well accommodate what is referred to by divers as “buddy-breathing.” Buddy-breathing involves use of a single mouthpiece by more than one diver, as may be necessary when the oxygen supply of one diver is low. In such situations, the mouthpiece is handed back and forth for alternating use by two divers. Customized mouthpieces of the prior art are not well suited for this practice. This is particularly true for mouthpieces having extended tooth engagement along either side of the diver's mouth.
Problems in manufacture can arise in the final customizing steps, that is, in fitting a customizable scuba-diving mouthpiece for a particular diver. While it is desirable to have a large area of customized tooth mouthpiece engagement, heating of the mouthpiece could lead to unacceptable deformation in areas not to be engaged by the mouth, for example, areas to engage the air conduit of a second-stage regulator. It would be desirable to provide a customizable mouthpiece not susceptible to such problems.
Another concern that has not been addressed in the prior art is the inability of the bitewings to function properly due to complete filling of the hollow bitewings or “bladders” or bladder cavity with gel-like substances. It has been determined, through extensive manufacturing and testing, that the presence of pressure relief channels on for both bitewing bladder cavities are required in order for bitewings to function properly. In this case, functioning properly is defined as conforming to the pressure and associated bite of the diver (user) into or onto the upper and lower surfaces of the bitewing thereby deforming the bitewing while allowing for conforming to the shape of the teeth that contact the bitewing. The pressure relief channels during compression allow air and or fluid (water, etc.) to be forced out of the bladder cavity (which is connected to the biteplate bladder cavity) and thereby allows for full or partial compression depending on the amount of gel or other similar substance originally within the bladder cavity. As the pressure and/or subsequent bite is released, the pressure relief channels essentially act as a bellows in that they allow air or other fluids to enter back into the cavities. Fully filled bladder cavities allow for at best extremely minimal compression and at worst no compression whatsoever in the presence of normal jaw pressures, thus defeating the purpose of filling the cavity with any substance to provide comfort and relieve jaw fatigue.
In order to create a full dental impression during or after bitedown, such as is possible with the present invention, the biteplate bladder cavity cannot be filled to capacity or overfilled, and actually may not require any filling whatsoever. It has been determined that in the case of an empty bladder cavity, the advantageous form, fit, and thus reduction of early jaw fatigue is comparable to that of an identical designed mouthpiece and biteplates that are partially filled. In both cases (unfilled and partially filled bladder cavities) the design requires the pressure relief channels connected to the bladder such that comfort is provided due to compression and relaxation of the biteplate cavities (normally fabricated from thermoplastics such as liquid silicone rubber and the like).
While there have been a number of efforts to make improved customizable scuba-diving mouthpieces, there has remained a clear need for significant improvements in the field of customizable scuba-diving mouthpieces that are both customizable and reusable specifically with regard to the dive rental and equipment sales business.